US4964955AExpiredUtility

Method of reducing pitch in pulping and papermaking operations

82
Assignee: CYPRUS MINES CORPPriority: Dec 21, 1988Filed: Dec 21, 1988Granted: Oct 23, 1990
Est. expiryDec 21, 2008(expired)· nominal 20-yr term from priority
Inventors:Richard S. LamarWilliam E. PrattKenneth E. WeberRobert E. Roeder
D21H 23/10D21H 21/02Y10S162/04
82
PatentIndex Score
54
Cited by
50
References
27
Claims

Abstract

A method of and substances for reducing pitch in pulping and papermaking operations, particularly in furnishes made by mechanical pulping processes containing wood pulp in amounts greater than about 10% by weight, are disclosed. The method comprises adding to a pitch-containing furnish a stable, water dispersible particulate composite substance prepared by irreversibly adsorbing a water soluble cationic polymer, e.g., a poly(diallyldimethylammonium chloride), onto an essentially water insoluble particulate substrate, e.g., kaolin, thereby rendering the cationic polymer insoluble and immobile, the cationic polymer being sufficiently electropositive so that the particulate composite pitch control substance exhibits a zeta potential of at least about +30 mV, and preferably from about +60 mV to about +80 mV, the amount of the composite substance added to the furnish being effective to finely disperse pitch for removal as finely-dispersed pitch-containing aggregates in a paper sheet produced from said furnish. Further improvements in pitch control can be achieved using these particulate composite pitch control substances together with alum and/or relatively high molecular weight alkylene oxide polymers, and other desirable effects, including improved fines retention, better drainage and lower waste treatment costs are also obtained when practicing this method.

Claims

exact text as granted — not AI-modified
We claim: 
     
       1. A method of reducing pitch in pulping and papermaking operations which comprises: (1) adding to a pitch-containing furnish a particulate composite substance comprising (a) a water soluble cationic polymer adsorbed onto (b) an essentially water insoluble particulate substrate, said polymer being sufficiently electropositive so that said composite substance exhibits a zeta potential of at least about +30 mV, and   (2) adsorbing pitch onto said composite substance to form discrete, finely dispersed pitch-containing aggregates in said furnish.   
     
     
       2. A method as recited in claim 1 in which said water soluble cationic polymer is sufficiently electropositive so that said composite substance exhibits a zeta potential of from about +60 to about +80 mV. 
     
     
       3. A method as recited in claim 1 in which said water soluble cationic polymer is a poly(dialkyldiallylammonium halide). 
     
     
       4. A method as recited in claim 1 in which said water insoluble particulate substrate is a phyllosilicate mineral. 
     
     
       5. A method as recited in claim 2 in which said water soluble cationic polymer is a poly(diallyldimethylammonium chloride) having an average molecular weight of from about 100,000 to about 500,000 and said water insoluble particulate substrate is kaolin. 
     
     
       6. A method as recited in claim 5 in which said kaolin has a particle size ranging from about 0.1 μm to about 40 μm. 
     
     
       7. A method as recited in claim 6 in which said composite substance is added to said furnish in an amount ranging from about 5 to about 200 lbs. per short ton of dry pulp in said furnish. 
     
     
       8. A method as recited in any one of claims 1-7, inclusive, in which a nonionic alkylene oxide polymer having a molecular weight of at least about 500,000 is also added to said pitch-containing furnish. 
     
     
       9. A method as recited in claim 8 in which said alkylene oxide polymer is a polyethylene oxide. 
     
     
       10. A method as recited in claim 9 in which the polyethylene oxide is added in an amount ranging from about 0.05 to about 2 lbs. per short ton of dry pulp in said furnish. 
     
     
       11. A method as recited in any one of claims 1-7, inclusive, in which alum is also added to said pitch-containing furnish. 
     
     
       12. A method as recited in claim 11 in which alum is added in an amount ranging from about 10 to about 80 lbs. per short ton of dry pulp in said furnish. 
     
     
       13. A method as recited in any one of claims 1-7, inclusive, in which a nonionic alkylene oxide polymer having a molecular weight of at least about 500,000 and alum are also added to said pitch-containing furnish. 
     
     
       14. A method as recited in claim 13 in which said alkylene oxide polymer is a polyethylene oxide. 
     
     
       15. A method as recited in claim 14 in which the polyethylene oxide is added in an amount ranging from about 0.05 to about 2 lbs. and alum is added in an amount ranging from about 10 to about 80 lbs., each per short ton of dry pulp in said furnish. 
     
     
       16. A method as recited in any one of claims 1-7, inclusive, in which, following the adsorption of pitch onto said composite substance, a paper sheet containing finely-dispersed pitch-containing aggregates is produced from the furnish. 
     
     
       17. A method as recited in claim 16 in which said furnish contains greater than about 10% by weight, based on the total dry weight of pulp in the furnish, of groundwood pulp. 
     
     
       18. A method as recited in claim 17 in which said furnish is a newsprint furnish. 
     
     
       19. A method as recited in claim 8 in which, following the adsorption of pitch onto said composite substance, a paper sheet containing finely-dispersed pitch-containing aggregates is produced from the furnish. 
     
     
       20. A method as recited in claim 19 in which said furnish contains greater than about 10% by weight, based on the total dry weight of pulp in the furnish, of groundwood pulp. 
     
     
       21. A method as recited in claim 20 in which said furnish is a newsprint furnish. 
     
     
       22. A method as recited in claim 11 in which, following the adsorption of pitch onto said composite substance, a paper sheet containing finely-dispersed pitch-containing aggregates is produced from the furnish. 
     
     
       23. A method as recited in claim 22 in which said furnish contains greater than about 10% by weight, based on the total dry weight of pulp in the furnish, of groundwood pulp. 
     
     
       24. A method as recited in claim 23 in which said furnish is a newsprint furnish. 
     
     
       25. A method as recited claim 13 in which, following the adsorption of pitch onto said composite substance, a paper sheet containing finely-dispersed pitch-containing aggregates is produced from the furnish. 
     
     
       26. A method as recited in claim 25 in which said furnish contains greater than about 10% by weight, based on the total dry weight of pulp in the furnish, of groundwood pulp. 
     
     
       27. A method as recited in claim 26 in which said furnish is a newsprint furnish.

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